Armstrong County, Pennsylvania
The most common soil here is Gilpin, on about 29% of the land: a channery silt loam, smooth, like flour. Weikert and Ernest come next.
About 64% of the land drains well, and 6% stays wet for long stretches; groundwater comes within two feet of the surface under 29% of it.
USDA rates 97% of the land very limited for a standard septic drain field, and 95% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 3% of the land floods occasionally or more, and bedrock lies within 40 inches under 57% of it.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
The soils you're most likely standing on
The biggest named soils in Armstrong County, Pennsylvania, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
The biggest mapped areas
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). The most common soil order is Ultisols — strongly weathered soils with clay-enriched subsoils, common in warm humid climates. This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in Armstrong County, Pennsylvania. Search your address to find the exact soil composition, drainage, and series details at your specific location.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Gilpin-Weikert channery silt loams, 25 to 70 percent slopes | 112K | Well drained | C | Very limited | Very limited |
| Gilpin-Weikert channery silt loams, 15 to 25 percent slopes | 39K | Well drained | C | Very limited | Very limited |
| Ernest silt loam, 8 to 15 percent slopes | 30K | Moderately well drained | C/D | Very limited | Very limited |
| Ernest silt loam, 3 to 8 percent slopes | 18K | Moderately well drained | C/D | Very limited | Very limited |
| Rayne-Gilpin channery silt loams, 8 to 15 percent slopes | 16K | Well drained | C | Very limited | Very limited |
| Wharton silt loam, 3 to 8 percent slopes | 13K | Moderately well drained | C/D | Very limited | Very limited |
| Bethesda very channery silt loam, 8 to 25 percent slopes | 12K | Well drained | D | Very limited | Very limited |
| Gilpin channery silt loam, 3 to 8 percent slopes | 12K | Well drained | C | Very limited | Very limited |
| Wharton-Gilpin silt loams, 15 to 25 percent slopes | 10K | Moderately well drained | C | Very limited | Very limited |
| Bethesda very channery silt loam, 25 to 75 percent slopes, very stony | 9K | Well drained | D | Very limited | Very limited |
| Cavode silt loam, 3 to 8 percent slopes | 9K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Water | 8K | Not rated | Not rated | ||
| Bethesda very channery silt loam, 8 to 25 percent slopes, very stony | 8K | Well drained | D | Very limited | Very limited |
| Rayne-Gilpin channery silt loams, 3 to 8 percent slopes | 8K | Well drained | C | Very limited | Very limited |
| Gilpin-Weikert channery silt loams, 8 to 15 percent slopes | 7K | Well drained | C | Very limited | Very limited |
| Wharton-Gilpin silt loams, 8 to 15 percent slopes | 7K | Moderately well drained | C | Very limited | Very limited |
| Cavode silt loam, 8 to 15 percent slopes | 7K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Gilpin-Weikert channery silt loams, 3 to 8 percent slopes | 7K | Well drained | C | Very limited | Very limited |
| Wharton silt loam, 8 to 15 percent slopes | 7K | Moderately well drained | C/D | Very limited | Very limited |
| Ernest silt loam, 15 to 25 percent slopes | 6K | Moderately well drained | C/D | Very limited | Very limited |
Soil Orders in This Area
The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.
What This Means
Building & Foundations
About 95% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, poor drainage in some areas. A geotechnical assessment is recommended before building.
Septic Systems
About 97% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.